This invention relates to dental accessories, and more particularly to apparatus, and a method for utilizing the apparatus, for deflecting the gingival area about a tooth prior to, and in order to render more accurate, the forming of negative impressions of relevant teeth in a patient's mouth.
In the restoration or replacement (by a prosthesis), of teeth or portions of teeth, as by the production of crowns or dental bridges and the like, it is common procedure to form an elastic mold from which a model is made for the formation of the dental prosthesis, or a cap or crown. This mold, or dental model, is generally formed as a negative impression, as an imprint of a prepared tooth and the surrounding gum area. The mold is then used in the construction of a model or case on which replacement teeth are made for the patient.
The prosthesis is formed from the negative impression in the mold. It is clear, therefore, that this mold impression must be accurate, in order to form the desirably accurate prosthesis. A sufficiently accurate mold for forming the prosthesis, must include not only impressions of the normally visible portions of the tooth to be molded, but also that portion of the tooth which normally extends just below the gum line or gingiva, i.e., the so-called "margin", of the tooth. Conventionally, this is obtained by packing a woven cord, or thread, around the margin of the tooth, so as to hold aside the soft tissue and to also dry out this socket adjacent the tooth, i.e., the sulcus. This is normally a laborious task where the dentist manually pushes in a strand of cord into the sulcus utilizing a dental probe moving around the circumference of the tooth. An alternative, where possible is to cut away the gum line from the tooth in order to gain access to the terminal portion of the prepared tooth.